001 /**
002 *
003 */
004 package org.wdssii.core;
005
006 import java.io.File;
007 import java.util.ArrayList;
008 import java.util.List;
009
010 import javax.xml.parsers.DocumentBuilder;
011 import javax.xml.parsers.DocumentBuilderFactory;
012
013 import org.apache.commons.logging.Log;
014 import org.apache.commons.logging.LogFactory;
015 import org.w3c.dom.Document;
016 import org.w3c.dom.Element;
017
018 /**
019 * This configuration class finds and uses the pertinent configuration
020 * information from the WDSS2/w2config directory.
021 *
022 * @author Lakshman
023 * @version $Id: W2Config.java,v 1.5 2007/10/11 15:23:01 lakshman Exp $
024 */
025 public class W2Config {
026 private static Log log = LogFactory.getLog(W2Config.class);
027
028 private static List<String> configDirectories = loadConfigDirectories();
029
030 private static boolean addDir(String dir, List<String> configDirectories) {
031 if (dir != null) {
032 if (new File(dir).exists()) {
033 configDirectories.add(dir);
034 log.debug("Will search w2config directory: " + dir);
035 return true;
036 } else {
037 log.info("Ignoring " + dir + " -- not there");
038 }
039 }
040 return false;
041 }
042
043 private static List<String> loadConfigDirectories() {
044 /*
045 * An environment variable W2_CONFIG_LOCATION $HOME $HOME/w2config,
046 * $HOME/WDSS2/w2/w2config, $HOME/WDSS2/w2config, etc. /etc/w2config
047 */
048 List<String> configDirectories = new ArrayList<String>();
049 log.debug("Looking for your w2config directories.");
050 String s = System.getenv("W2_CONFIG_LOCATION");
051 if ( s != null ){
052 String[] locations = s.split(":");
053 for (String location : locations){
054 addDir(location, configDirectories);
055 }
056 }
057 s = System.getProperty("user.home");
058 if (addDir(s, configDirectories)) {
059 addDir(s + "/w2config", configDirectories);
060 addDir(s + "/WDSS2/w2config", configDirectories);
061 addDir(s + "/WDSS2/src/w2/w2config", configDirectories);
062 }
063 addDir("/etc/w2config", configDirectories);
064 return configDirectories;
065 }
066
067 /**
068 * will search the config directories for the first file that matches the
069 * given filename. can return null.
070 *
071 * For example, passing colormaps/Reflectivity, you will get a File
072 * corresponding to /etc/w2config/colormaps/Reflectivity
073 */
074 public static File getFile(String filename) throws ConfigurationException {
075 for (String configDir : configDirectories) {
076 String s = configDir + "/" + filename;
077 File f = new File(s);
078 if (f.exists()) {
079 if (log.isInfoEnabled()) {
080 log.info("Using config file " + s);
081 }
082 return f;
083 }
084 }
085 String error = "Could not find config file " + filename;
086 log.error(error);
087 throw new ConfigurationException(error);
088 }
089
090 /**
091 * Parse and return the XML Dom element corresponding to a partial file
092 * name.
093 *
094 * For example, passing colormaps/Reflectivity, you may get the DOM element
095 * from /etc/w2config/colormaps/Reflectivity
096 */
097 public static Element getFileElement(String filename)
098 throws ConfigurationException {
099 File f = getFile(filename);
100 try {
101 DocumentBuilder parser = DocumentBuilderFactory.newInstance()
102 .newDocumentBuilder();
103 Document doc = parser.parse(f);
104 return doc.getDocumentElement();
105 } catch (Exception e) {
106 throw new ConfigurationException(e);
107 }
108 }
109 }